Method and apparatus for destroying documents

ABSTRACT

A method and apparatus for destroying documents in which opposed slitter rollers are provided which slit a document into longitudinal strips while the rollers are provided with means for cutting each longitudinal strip into a plurality of short sections.

United States Patent [191 Goldhammer 1 Jan. 14, 1975 4] METHOD AND APPARATUS FOR DESTROYING DOCUMENTS I [76] Inventor: Albert Goldhammer, Zum l-lecht 40,

7773 Nussdorf/Uberlingen, Germany 221 Filed: Mar. 14, 1973 211 Appl. No.: 341,294

[30] Foreign Application Priority Data Sept. 29, 1972 Germany 2247901 [52] US. Cl. 241/27, 241/236 [51] Int. Cl. B02c 18/06 [58] Field of Search 241/236, 243, 27, 29, 30

[56] References Cited UNITED STATES PATENTS Guettler 241/236 X 3,529,782 9/1970 Liebman 1 A l l 241/236 X 3,630,460 12/1971 Goldhammer 241/236 3,664,592 5/1972 Schweigert 241/236 X FOREIGN PATENTS OR APPLICATIONS 1,226,633 2/1960 France 241/236 Primary ExaminerGranville Y. Custer, Jr. Attorney, Agent, or Firm-Albert L. Jeffers; Roger M. Rickert [57] ABSTRACT A method and apparatus for destroying documents in which opposed slitter rollers are provided which slit a document into longitudinal strips while the rollers are provided with means for cutting each longitudinal strip into a plurality of short sections.

5 Claims, 5 Drawing Figures PATENTEB JAN 1 4mm sum 1 or 5 PATENTEB JAN 1,4!975 7 saw an! 3 METHOD AND APPARATUS FORDESTROYING DOCUMENTS This invention relates to a method and apparatus for destroying documents and, in particular, to the destruction of documents without burning.

Heretofore, documents have been destroyed without burning by cutting the documents into narrow strips. While destroying documents in this manner does subdivide the documents into small pieces, the narrow strips of paper tend to roll up into balls which are rather difficult to handle while, furthermore, the disadvantage exists that whole lines of written material can show up on a long strip.

With the foregoing in mind, the present invention proposes a method of destroying documents in which the documents are not only cut into narrow strips, but the strips are also cut or torn transversely into shorter pieces.

A further object is the provision of an apparatus for destroying documents in which the documents are cut into strips while simultaneously the strips themselves are subdivided into shorter sections.

It is also an object to provide a method and apparatus for destroying documents by forming the documents into strips and then cutting the strips into shorter sections in which the destroying operations on the document are carried out in one single working operation in a single machine.

BRIEF SUMMARY OF THE INVENTION According to the present invention, a document destroying, or shredding device, is provided in which two counter rotating rollers are provided, each having cutting discs interleaved with the cutting discs of the other roller so that a document fed between the rollers will be cut into long narrow strips.

According to the present invention, the individual H discs have interruptions on the peripheries thereof and the trailing edge of each interruption is arranged to cut or tear off a strip of the document so as to form the strips into short sections. The cutting or tearing of the strips into shorter'sections takes place simultaneously with the slitting of the document into long strips.

The foregoing objects as well as other objects and advantages of the present invention will become more clearly apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a somewhat schematic fragmentary plan view showing a document destroying device according to the present invention.

FIG. 2 is a sectional view indicated by line II-Il on FIG. 1.

FIG. 3 shows a portion of a document which has been partially destroyed in the apparatus.

FIGS. 4 and 5 are fragmentary views drawn at enlarged scale and showing the manner in which the device operates.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings somewhat more in detail, the document destroying device according to the present invention comprises a pair of rollers 3 and 4 rotatable on respective axes 1 and 2 and which axes are parallel. The rollers are geared together so as to counter rotate and are rotatably supported in a frame 5 as by antifriction bearings with the bearings of one roller being axially displaced from the bearings of the other roller so that bearings of substantial size can be employed while at the same time the rollers can be arranged in the proper spaced relation.

Each roller is provided with cutting discs 6 which have cylindrical peripheries and substantial radial edges so as to form sharp corners at the axial ends of the respective discs. The discs 6 are in spaced relation on the respective rollers and interleave with one another so that each pair of adjacent axial edges of the discs form a slitter. A document fed between the rollers will, thus, be cut into relatively thin longitudinal strips by the cutters.

Each cutter roller may be manufactured from tubular material by suitable machining processes or the central portion of each roller may be tubular with the discs mounted thereon in fixedly spaced relation.

According to the present invention, each disc is provided about its periphery with notches 7 with each notch having a trailing side 7 which intersects the periphery of the respective disc at an angle of from about to about The angle of intersection of the trailing side of each notch with the circumference of the respective disc forms a transverse cutting edge for forming a lateral incision in the document being shredded.

A nose angle of greater than 90 would give such a blunt cutting edge that the document would not be cut and a nose angle sharper than 75 has been found to be so sharp as to be easily damaged by paper fasteners or clips or the like that might pass through the machine with the document.

Advantageously, the notches are formed in the discs by taking helical cuts around the assembled cutting roller to form a helical notch thereabout. The angle of inclination of the trailing side of the notches is easily obtained by. imparting the proper angle to the cutter forming the groove and by forming the grooves helically about the rollers. The notches are staggered relative to each other and, thus, progressively cut the document as it passes between the rollers. By so staggering the notches the driving energy required to drive the rollers remains substantially constant and thereby a smaller.

drive motor is required and the entire unit can be made of relatively light construction.

With reference to FIGS. 3 to 5, FIG. 3 shows a portion of a document which is partially shredded. In FIG. 3, the longitudinal slits being formed in the document are indicated at 12 while the transverse cuts in the document are indicated at 14. Slits 12 are made by the edges of the cutter discs whereas transverse incisions 14 are formed by the noses at the trailing sides of the notches 7'.

FIGS. 4 and 5 show a document D passing downwardly between rollers 3 and 4. The document has the lower end thereof cut into strips while in the region 10 of the document immediately below the cutting edge on nose 7 the document is not slit. The document, how ever, is bent over nose 17 at the advancing side of notch 7' and is, thus, held taut so that nose 7 will make an incision in the document when the nose passes on between the discs on roller 4.

The cutter discs may be provided with recesses 20 in advance of the notches therein which engage the respective paper strip and draw it tight against nose 7. Recesses 20 may be engaged by members on the other roller, but even if nothing else engages in recess 20 the paper strip will still be clamped therein as illustrated in FIG. 4 thereby to draw the respective strip into a state of tension over nose 7.

Referring again to FIG. 3, in connection with FIGS. 4 and 5, the fragment of the document D shown in FIG. 3 has a longitudinal strip identified at A which corresponds substantially to the condition of the document with rollers 3 and 4 in the FIG. 4 position, that is, with notch 7' having the nose portion 7 just about to enter between the pertaining discs on roller 4. When the rollers have turned to about the position shown in FIG. 5, the strip being cut will correspond to that indicated at B in FIG. 3.

It will be noted that the portion of the document indicated at 10, and which is indicated by the same reference numeral on FIG. 3, is disposed between the incision made by the respective nose 7 and that portion of the document which has previously been slit.

Thus, in FIG. 4, an incision is being made by nose 7 and a substantial length of document in advance of the nose is unslit while in FIG. the nose has formed the incision and slits have commenced to form behind the nose while the portion of the document in advance of the nose which is unslit is substantially reduced in length. v

The present invention provides for the reduction of a document into narrow longitudinal strips while simultaneously interrupting each longitudinal strip to form it into short sections.

The method of reducing documents according to the present invention has the further advantage that the shredded documents can rapidly be reduced in a further process by the use of putrefication bacteria and the thus reduced document material can be utilized as humus.

In particular, the shredding of the documents according to the present invention preserves a high degree of secrecy because the short sections into which the strips are formed will be thoroughly mixed up and the documents cannot be reassembled.

The usual process for insuring maximum secrecy is to cut the documents into extremely narrow strips, down to as little as one millimeter wide, but according to the present invention, the document particles may be as wide as 4 millimeters with each section of each strip being on the order of to millimeters in length.

Modifications may be made within the scope of the appended claims.

What is claimed is:

1. The method of destroying a document which comprises: cutting the document into narrow longitudinal strips while simultaneously forming each strip into short sections, the longitudinal strips being formed by making spaced parallel slits in the document, and the longitudinal strips being formed into short sections by making transverse incisions in the document each of which extends obliquely from the path of one slit to the path of an adjacent slit, the incisions pertaining to each strip being formed in the document in longitudinally distributed relation with each incision staggered relative to laterally adjacent incisions, the transverse incisions being formed in the document in advance of the forming of the slits intersected thereby and simultaneously with the forming of the slits.

2. In a document shredder; a pair of counter rotating cutter rollers, each roller comprising axially spaced cutter discs having radial side faces and a cylindrical periphery with axial edges and with the cutter discs of each roller fitting closely between the cutter discs of the other roller whereby each adjacent pair of cutter disc edges forms a slitter, and means on the circumference of each cutter disc comprising the trailing edge of at least one axial notch formed in the periphery of the cutter discs pertaining to at least one roller for forming transverse interruptions in strips of the document formed by adjacent slittcrs, each said notch being inclined from side to side and being displaced circumferentially from the notch in adjacent cutter discs in such a manner that the notch pertaining to the cutter discs of each roller define at least one helical groove in the periphery of the respective roller, the side of each notch which is trailing when the respective roller is rotating forming an included angle with the periphery of the respective cutter disc where the side intersects the periphery which is smaller than 90 and greater than 75 3. A document shredder according to claim 2 in which said rollers are provided with tensioning means comprising peripheral recess means formed in each said cutter disc in advance of each said notch for developing tension on the strips of a document being shredded.

4. A document shredder according to claim 2 in which said rollers are tubular.

5. A document shredder according to claim 2 which includes frame means, and bearings supporting the rollers in the frame means, adjacent ones of said bearings being disposed in axially displaced relation. 

1. THE METHOD OF DESTROYING A DOCUMENT WHICH COMPRISES: CUTTING THE DOCUMENT INTO NARROW LONGITUDINAL STRIPS WHILE SIMULTANEOUSLY FORMING EACH STRIP INTO SHORT SECTIONS, THE LONGITUDINAL STRIPS BEING FORMED BY MAKING SPACED PARALLEL SLITS IN THE DOCUMENT, AND THE LONGITUDINAL STRIPS BEING FORMED INTO SHORT SECTIONS BY MAKING TRANSVERSE INCISIONS IN THE DOCUMENT EACH OF WHICH EXTENDS OBLIQUELY FROM THE PATH OF ONE SLIT TO THE PATH OF AN ADJACENT SLIT, THE INCISIONS PERTAINING TO EACH STRIP BEING FORMED IN THE DOCUMENT IN LONGITUDINALLY DISTRIBUTED RELATION WITH EACH INCISION STAGGERED RELATIVE TO LATERALLY ADJACENT INCISIONS, THE TRANSVERSE INCISIONS BEING FORMED IN THE DOCUMENT IN ADVANCE OF THE FORMING OF THE SLITS INTERSECTED THEREBY AND SIMULTANEOUSLY WITH THE FORMING OF THE SLITS.
 2. In a document shredder; a pair of counter rotating cutter rollers, each roller comprising axially spaced cutter discs having radial side faces and a cylindrical periphery with axial edges and with the cutter discs of each roller fitting closely between the cutter discs of the other roller whereby each adjacent pair of cutter disc edges forms a slitter, and means on the circumference of each cutter disc comprising the trailing edge of at least one axial notch formed in the periphery of the cutter discs pertaining to at least one roller for forming transverse interruptions in strips of the document formed by adjacent slitters, each said notch being inclined from side to side and being displaced circumferentially from the notch in adjacent cutter discs in such a manner that the notch pertaining to the cutter discs of each roller define at least one helical groove in the periphery of the respective roller, the side of each notch which is trailing when the respective roller is rotating forming an included angle with the periphery of the respective cutter disc where the side intersects the periphery which is smaller than 90* and greater than 75* .
 3. A document shredder according to claim 2 in which said rollers are provided with tensioning means comprising peripheral recess means formed in each said cutter disc in advance of each said notch for developing tensIon on the strips of a document being shredded.
 4. A document shredder according to claim 2 in which said rollers are tubular.
 5. A document shredder according to claim 2 which includes frame means, and bearings supporting the rollers in the frame means, adjacent ones of said bearings being disposed in axially displaced relation. 